In the field of communication equipment, such as cellular phones, there is a need to provide for a pluggable connector that will allow the equipment to switch from an internal antenna to an external antenna, and back, i.e. from cradle to hand held unit.
There are many kinds of apparatus that are known which require switching from one antenna to another, and there are many types of interconnect arrangements which will switch automatically as, for example, when a portable device is inserted into a higher powered unit in a vehicle. In such a case, the portable antenna may be either inadequate or too shielded by the vehicle body for transmission and reception over longer distances. Such an arrangement is shown in U.S. Patent No. 3,946,390. In that arrangement, a coaxial connector on the end of a coaxial cable activated a conductive plunger which disconnected the internal antenna from the radio circuit and connected an external signal source from an external antenna to the radio circuit.
U.S. Patent No. 4,286,335, also relying on a plunger arrangement to disconnect one antenna, represents an improvement thereover. Briefly, the apparatus thereof is contained within an insulating housing. Mounted on this housing, preferably releasably, is a small coaxial antenna. The center conductor of the antenna contacts the resilient center conductor of a coaxial switch/connector having a conductive housing, the resilient conductor being coupled to the center conductor of a coaxial cable for bringing received signals to the radio circuitry of the apparatus. When the apparatus is inserted into an external device such as a mobile radio in a vehicle, another coaxial cable is automatically coupled to the apparatus with the cable center conductor actuating a spring-loaded plunger to disconnect the small antenna center conductor from the resilient conductor of the switch/-connector and to connect, instead, an external antenna to the apparatus circuitry.
The present invention avoids the more complex arrangements of the prior art, while providing the capability to switch from one antenna to another, and carry power and in line connection from cradle to hand held unit, for example. Additionally, by the construction hereof, a shielded low DB loss system is provided. This will become apparent in the description which follows, particularly when read in conjunction with the accompanying drawings.